Ligandassembly and chirality transfer guided by DNA modified with enantiomerically pure [2.2]paracyclophanes

Abstract

Enantiomerically pure (R_p)- and (S_p)-4-azido[2.2]paracyclophane was incorporated into DNA using copper-catalysed azide–alkyne cycloaddition. While these modifications caused destabilisation of the duplexes, those that had the paracyclophane arrayed in a zipper-like motif were still stable at room temperature. The interactions of several modified duplexes with an achiral cationic perylenediimide were investigated. UV-VIS and CD data indicate that the transfer of chirality from paracylophane–DNA to the perylene is dependent on the arrangement of the chiral paracyclophanes in the preformed duplex. Significant thermal stabilisation of paracyclophane–DNA is observed upon addition of perylene (ΔT_m = +8.0…19.0 °C), while no change in thermal stability is detected for the unmodified duplex. These findings pave the way for the design of DNAs with extended chiral properties which can further be translated into chemical transformations and into the design of chiral optical arrays.